According to an insider, the Alias alum, 49, who shares Violet, 16, Seraphina, 12, and Samuel, 9, with Affleck, was "furious" when he cut short the family’s recent Thanksgiving get-together so he could spend most of the day with J.Lo’s brood.
The Tender Bar star, 49, "didn't let Jen know ahead of time that he was planning to leave early, so she was a bit blindsided," spills the insider. "They’ve always had a pact to co-parent on holidays, so for him to duck out that way didn’t sit well with her."
Then things took a dramatic turn. "Word is, Jen was so riled up that she called J.Lo to give her a piece of her mind," claims the insider. As far as Garner is concerned, "Ben can have whatever relationship he chooses with J.Lo," explains the insider. "But when it comes to their kids, he has to put them first."
However, Affleck's answer to the issue, says the insider, is just to have his kids join him, J.Lo and her twins [Emme and Max, 13]. "He doesn’t see the problem with blending families, which has left Jen even more upset. It’s a sensitive topic."
For her part, J.Lo "was really taken aback by the whole thing and felt that Ben could have handled the situation better," shares the insider. "She doesn't think she deserved to be targeted like that."
Now, the Hustlers star, 52, is pressuring her beau to tell his ex that "she should be ready for dynamics to change, because they’re a solid couple and they’ll make their own holiday traditions," the insider continues. "J.Lo's happy to include his kids."
An OK! insider previously spilled that the blended family is gearing up to spend Christmas together, with the source pointing out that while Garner and Lopez may never be the best of buds, they found "common ground" over doing what's best for their children.